Picture transmission system



' 3 F. MIDDELRAAD 2,024,051

PICTURE TRANSMISSION SYSTEM Original Filed June 20, 1929 7 Sheets-Sheet 1 U N B "3 iNVENTOR EL-Mp'zidelradd ATTORNEY W MW Dec. 10, 1935. F. MIDDELRAAD PICTURE TRANSMISSION SYSTEM Original F'iled June 20, 1929 7 Sheets-Sheet l// Zfa 4 INVENTOR EL .Mz'ddelraad,

BY 4 4 m) ATTORNEY I Dc. 10, 1935. F. L. MIDDELRAAD "2,024,051

' PICTURE TRANSMISSION SYSTEM Original Filed June 20, 1929 '7 Sheets-Sheet 4 E 2 2 5 e v I L W 8 h E 19 gwve ntoz rm, i

F. L. MIDDELRAA D PICTURE TRANSMISSION SYSTEM Original Filed June 20, 1929 '7 Sheets-Sheet 6 28 f 263 26d :50 26b 26a 310 4 INVENTOR F: L- Mi dde ZZZ/7L- Dec. 10, 1935. F. 1.. MEDDELRAA 2,024,051

PICTURE TRANSMISSION SYSTEM Original Filed June 20, 1929 7 SheetsSheet 7- l 39 I i H H: l E II E l 364 Q l I I I 1 1 l I l i i i :1 i 1 I 2 I 1 3g i l T i i l .1 l V36 O 1 l --3 l I 3 l I I i s I l L l 322 v 362 G b \Y 323 I0 36:

10a 1 l 1 1 0 1 I l INVENTOR ELaT/WdrMd,

ATTORNEY Patented Dec. 10, 1935. 7

PICTURE TRANSMISSION SYSTEM Franciscus Leonardus Middelraad, Toronto,

' Ontario, Canada Application J une 20, 1929, Serial No. 372,490 Renewed April 19, 1934 10 Claims. (01. 178-6) My invention relates to a system for the transmission and reception of pictures or scenes between distant points.

In known systems for the transmission of pictures scanning device's are employed which traverse the picture in a series of parallel strips, and the photo-electric current produced varies in accordance with the changes in light intensity of successive portions of the strips. An object .0! my invention is to devise a scanning arrangement in which the picture is analyzed into a plurality of separate elementary areas or dots which remain stationary and which when exposed in succession to the light-cell produce a photoelectric current of a periodic character.'

A further object of my invention is to devise a novel photo-electric cell for conserving and utilizing the light .of a picture image to the greatest efliciency.

Still another object of my invention is to devise a scanning arrangement employing a multiple photo-electric cell having a sensitive area sufliciently large to receive an image of the picture to be transmitted, and to provide commutator means for connecting the elementary cells of the multiple cell to the transmitting apparatus in succession;

A further object is to devise a scanning ar-' rangement in which an image of the picture to be transmitted is projected upon a number of photoelectric cells having an effective area lessthan the image area,and to provide means for shifting the photo-electric cells whereby the entire image area may be scanned by a lim'ted number of photo-electric cells.

My invention also has for an object the provision of a scanning device making it possible to employ a multiple photo-electric cell in which the individual cells have physical dimensions larger than the elementary areas of the image projected upon the multiple celi..

My invention also relates to a system for indicating the condition of synchronism between the transmitting and receiving stations.

A further object oi my invention is to devise a scanning arrangement employing two crossed groups of separately operable shutter elements,-

and in which the number oielementary areas which may be exposed successively is equal to the product of the number of shutters in one group times the number in the-other group;

A further object of my invention is to devise a system, for the transmission and reception of pictures in colors. 7

My invention is illustrated in the accompanying drawingsinwhich:

Figure 1 is a side view ot one, iorm oirny invention'with one side of the enclosing housing- I Y l is provided at one end with aopening 6 removed;

I my invention Figure 1a is a front view of the apparatus shown in Figure l'with the housing removed;

Figure 2 is a side view of another form of my invention with one side of the enclosing housing removed; Figure 2a. is an end view of 'the apparatus shown in Figure 2 with the enclosing housing re moved; Figure 3 is a fro t view of a third form of my invention; 1

Figure 3a is a side elevation of Figure 3;

Figure 3b is a plan view of Figure 3;

Figure 4 is an elevation, partly in cross section, of a fourth form of my invention;

Figure 5 is an elevation, partly in cross section, of a fifth form of my invention;

Figure 6 is a side elevation of another form of my invention; I

Figure '7 is a side elevation of a modification of the arrangement shown in Figure 6;

Figure 8 is an enlarged view showing the details of construction of the bands employed in Figures -6 and 7; 3

Figure 8a is a detailed view of a typical slat element employed in Figure 8; v '25 Figure 8b illustrates the manner in wliichthe photo-electric cell and 1 the incandescent lamps are mounted in the slatsof the movable belt shown in Figures 6, '1 and 8; I

Figure 91s a schematic diagram of the apparatus employed for indicating synchronism between the transmitting and receiving stations;

Figures 10a, 10b, l qc, 10f and 10g illustrate typical arrangements of perforations in bands A and B for use in connection with the double-band arrangements shown in Figures 2, 4 and 5; Figure 10d illustrates the arrangement or periorations in band C and screen 4 as employed in the arrangement shown in Figure- 1;

Figure 106 illustrates the arrangement of per- 4 iterations-in band A employed in Figures l4 and a Figure 11 is a front view of another form of in which'the scanning operation is accomplished by' the simultaneous opening of shutters or doors having a width'equal to' that of an elementary picture area; f v

Figure 12 is a side view of Figure ll'with the scanning door assembly shown in cross section along the line "-12;

Figure 13"is a perspective view showingthe two sets of doors arran ed at right angles to eachother;

Figure 14 is a side view oi-another iormiof my invention for the transmission of picture's'in colas omand l, w

overwhich is fitted camera hood 2 containing an objective lens 3 which is adapted to form an image of the object or scene to be transmitted upon a the sensitive area of a photo-electric cell 5. A

flexible, opaque, endless band C is arranged to pass between screen 4 and lens 3a, and is driven by a pulley 6 which in turn is driven by a motor I.

Band C is provided with a number of perforations Cl, C2, etc. (see Fig. 1a), spaced along the in screen 4, light is fadmitted'to housing I "with-- length of the band a distance equal to the height of the picture screen, each successive perforation being displaced horizontally with respect to the last a distance slightly greater than the width of a perforation. For example, if the screen 4 and the picture area is provided with 8 rows of eight perforations each, then band C will be provided with eight perforations, each displaced from the next along the length of the band by a distance equal to the height of the screen and being displaced horizontally to coincide with one of the rows of perforations in screen 4; While for the purpose of illustration I have shown. the elementary areas as being rather large with respect to the picture area, it will be understood that the w size and the spacing of the elementary areas may .be made as small as desiredin order to obtain satisfactory detail in the reproduced picture. In order to accommodate the required length of band in the relatively small housing I, the band may be passed back and forth over a. number of idle pulleys 8. It will be apparent that pulley 6 may I be provided with two rows of driving sprockets or teeth engaging suitable driving perforations on band C in the same manner as motion picture film drive.

Operation of the scanning arrangement shown in Figures 1 and 1a is as follows:

The picture or object to be transmitted is imaged upm screen 4 by objective lens 3.. The band C is driven at a. suitable constantspeed past screen 4. Only oneperforation of band C will be opposite screen 4 at any given instant. As explained above, each perforation-in, band C is arranged to travel over a row of perforations in screen 4.' For example, perforation Cl passes over the first vertical row of perforations in screen 4, and as it passes out of'the picture area, perforation C2 passes'over the second vertical ,row 'of pe'rforations'in screen 4, and the same operation takes place-with respect to the remaining perforations in band C until all the perforations in screen 4 have been covered. As a perforation in band Cpoincides with a perforation an intensity correspondingto the elementary area of the image of the picture at that particular point. This light is focused upon' the sensitive area of photo-electric cell 5 by condensing lens 3a. It will be seen that by the use-of stationaryscreen 4, the elementary areas of the picture remain stationary during the scanning operation, and as band C passes in front of the screen, light from each elementary area is permitted to influence the photo-electric cell 8 in succession. It will be understood that cell 5 is connected to suitable electric translating circuits pulley l 'fifth perforation inrow Bl and that periodic current variations will be produced in these circuits coresponding in intensity to the light variations of the successive elementary areas of the picture. The current variations are amplified and transmitted to the receiving apparatus by any of the methods well known to those skilled in the art. Due to the periodic chanacter of the current, caused by the periodic coincidence of the perforations in the stationary screen and the perforations in the movable scan- 10 ning band, under certain conditions it will be feasible to employ transformer-coupled amplifiers for amplifying the current. At the receiving station, the apparatus is the same as at the transmitting station, except that the cell 5 is replaced by an electric lamp energized by the received 'current. The transmitting and receiving devices must be driven in synchronism, which may be accomplished by any of the well known systems employed for this purpose.

It will be apparent that the screen 4 may be positioned behind band C instead of in front of it as shown in Fig. 1.

In the arrangement shown in Figures 2 and 2a, the screen 4 has been omitted and two perforated bands are employed instead of one. The band A is driven by pulley 6 and is provided with a series of perforations arranged in oblique lines spaced apart a distance equal to the screen height, as shown at Al and A2 in Figure 2a. Band B is arranged to be driven in step-by-step movement by the shaft of which is provided with a multi-tooth gear engaging a mutilated (singletooth) gear mounted on the shaft of pulley 9. Band B is provided with horizontal rows of perforations displaced apart a distance equal to the picture height, as indicated at BI and B2 in Figure 2a. i v

Operation of the arrangements shown in Figs;

2 and 2a. is as follows: .40

The outline of the picture area is indicated by the dotted square P in Figure 2a. Only one row of perforations in band B lies within the picture area at any given instant. As band A passes in front of the picture area, the perforations on this band coincide with the perforations on band B in succession from left to right. For example, the

is partially coinciding with the fifth perforation in the row Al of band A. The sixth perforation will be the next to coincide. The gearing arrangement connecting pulleys 8 and ill for the intermittent drive of band Bis such that band is moved vertically a distance equal to the distance between adjacent perforations in band B, or a distance slightly larger than the diameterof a perforation. It will thus be seen that by continued operation of the scanning device, the entire picture area will be effectively analyzed into stationary elementary picture areas, and these areas will be successively scanned.

It will be understood that instead of driving band B by'intermittent movement, this band may be driven at a constant speed by providing a suit- I Figs. 3, 3a and 3?). Elements corresponding to like elements in Figures 1 and-2 are indicated ,made of potassium or other photo-electric metal, or they may be made of non-sensitive metal and characters. In this arby the same reference band B is trained over rangement, the opaque rolls on shafts la and l 51;, and band A is trained driving rolls may be provided with driving teeth or sprockets engaging these perforations.

Band B- isprovided with. a number of rows of perforations Bl, B2, B3, etc., arranged at .right angles to the length of the band and spaced apart along the band a distance equal to the height of the picture area. Band A is likewise provided with a number of rows of perforations Al A2, A3, etc., spaced apart along the length of the band adistance equal to the width of the picture area. The picture area, or the area of the image produced by camera 2, is indicatedby the dotted square P in Figure 3. The perforations in the bands are preferably round and are of a size equal to an elementary area of the'picture area P.

Operation of the arrangement shown in Figures 3, 3a and 3b is as follows:

With the bands in the position shown in Figure 3.'the perforation at the left of row B2 in band B coincides with the perforation at the top of row Al in band A, and light is admitted from that part of the image which lies immediately opposite these two perforations.

As band B moves upward; the single-tooth gears lic engage the multi-tooth gears A to move to the right a distance slightly greater than the diameter of a perforation. The perforation second from the left in row Bl now coincides with the bottom perforation in row Al. Continued the entire row Al to be traversed by the second perforation from the left in row Bl. When the row Bl reaches the top of the picture area, the band A is again moved to the right a. distance slightly greater than the diameter of a perforation, and the row Al is again traversed by the third perforation in the neat row of perforations in band B. This operation continues until the entire picture area has been covered. The light admitted to the camera is condensed by lenses 3a and projected upon the. photo-electric cell 5,

wherenit produces corresponding current varia'- tions in suitable electric circuits, which current variations are transmitted in the well known manner to the receiving station.

It is apparent that the position of the single tooth on gears 150 is not correctly shown with respect to the relative positions of the rows of perforations on bands A and B, but the gears have been shown in the position illustrated for the sake of clearness of illustration. The correct Y position for the single tooth on gears live in Figure 3 is just at the point of engagement with a tooth on gears 16a.

In Figure 4 there is shown a special form ofv photo-electric cell for use in connection with the double band arrangement disclosed in Figure 2. The novel cell comprises a gas filled glass envelope ll having parallel front and back sides Hit and llb, and being sufficiently large in'area to cover the camera opening in housing I. The back side llb of the container is covered with a plurality of photo-sensitive cathode elements l2 I60 and cause band movement of band B upward causes .are arranged in checker-board fashion to complet'ely cover the area upon which the image of the picture-is to be formed, each cathode element being of sufficiently small dimensions to constitute one elementary area of the picture. Within the cell ll there is mounted a screen or grid anode ll extending over the entire picture area and being provided with a terminal conductor l3a. Bands A and B are arranged to pass over the contact studs Ila at the rear of the cell, and these bands are provided with perforations as described above in connection with Figs. 2 and 2a. A conducting plate It is mounted parallelto the cell II on the opposite side of bands 'A and B, and a number of spring contact fingers a, corresponding in number and position to 2b the photo-electric cathodes, are supported from this plate and the free ends of which press bands A and B against the contact studs l2a.

Operation of Fig. 4 is as follows: The picture g or scene to be transmitted is imaged upon the area covered by the cathodes II .by means of the camera 2. Each cathode element will be energized or excited in accordancewith the intensity of the light falling upon it at any given instance. Terminal conductors Ba and llb are connected to electric amplifying and transmitting circuit of, usual design for the transmission 'of currents originating from the cell. Due to the particular arrangement of perforations on bands A and B, the spring contact fingers Ila are held out of 40 contact with the cathode studs I20. except when a perforation on band A coincides with the perforation on band B. The perforations are so arranged-that there is only one coinciding position in the picture area at any given instance, and therefore only one cathode element I2 is connected in the transmitting circuit at any given time. As explained above in connection with Figs.

2 and2a continued operation of bands A and B will eifect the connection of all the elementary photo-electric cells into the transmitting circuit in succession. The current supplied to the input of the transmitting circuit .will be proportional to the'light intensity of an elementary area of the picture corresponding to the position of the particular cell whose circuit is completed.

The arrangement shown in Fig. 5 is somewhat like that shown in Fig. 4 except that the cathode elements are all connected permanently to the terminal conductor llb, and thecell is arranged behind bands A and B in such manner that only one point of light is permitted to pass to the cell at any given instant. In this arrangement 'all the elementary photo-electric cells are connected in parallel to the transmitting circuit but 65.

only one cell is energized at a time by light passing through coinciding perforations on hands A and B. Accordingly, the intensity of the current transmitted at any instant willbe proportional to the light admitted through the coinciding perpossess an advantage over the single-cell arrangements shown in Figs. 1, 2 and 3, in that, since the elementary cellsare located in the image plane, all the light in each elementary area of the picture image is efiective in operating the cell.

Both the arrangements shown in Figs. and 6 .may be used as receiving devices by replacing the multiple cell by a lamp board having lamps mounted in the places occupied by the elementary cells, and connecting the terminals I 3a and Nb to the output of the receiving amplifier.

In Figures 6 and 7, I have shown other forms of my invention for r of operation ,of the photo-electriccells at the transmitting station and the light sources or lamps at the receiving station.

In the arrangement shown in Fig; 6, the stationary photo-electric cell and condensing lens has been replaced byra flexible slat-belt D trained over rolls Ila and Ilb and carrying groups 9f photo-electric cells El, E2, E3, E4, etc., at spaced points along the belt. I

The slat-belt D comprises a flexible backing strip Da to .which is attached wooden slats or laths Db. The slats which do not cary cells may be straight slats as shown in Fig. 8. The

slats which carry the photo-electric cells are provided on their outer surface with a metallic covering Dc which may be shaped to form the screw-sockets for receiving the photo-electric cell E, or the electric lamp L, see Fig. 8b. Both the cells and the lamps are preferably constructed with screw plug connectors after the fashionof an ordinary electric lamp. The cathode K of the cell is provided with 'a central contact pin Ea which extends-to the rear of the belt D, and is adapted, to contact with a plurality of spring contact elements I8 mounted upon a conducting plate I8a in the rear of the camera 2. The arrangement of one cell group is illustrated in Fig. 8. For the purpose'of illustration, I have shown one group of Il cells mounted on three slats of special outline. Referring to Fig. 8, slat (a) carries cells I, 2, 3, 4, 5, 6, and l; slat (b) carries 8,9, I0, II,

I2, I3, and I4; and slat (c) carries cells I5, I6 and Il. Slat d does not carry cells but has a special shape to conform to the shape of slat (a). Slat (e) does not carry cells and is a plain straight slat. The shape of slat (b) is shown in Figure 8a The group E2 of photo-electric cells is the same as group EI shown in Figure 8, and is spaced from group EI along the slat-belt D a distance equal to a screen height, that is, a distance equal to the width of the picture on the belt D. Cell groups E3 and E4 are like cell groups EI and E2 and are likewise spaced apart a distance equal to a screen height.

The grid or anode G of the cell E is connected to the screw shell of the plug of the cell and is,

therefore, connected to the metallic plate Dc of the slat. A conducting rod or bar I9 is provided along one edge of the belt D and carries a number of spring contact fingers I 9a arranged to en=-" gage the metallic. strips Dc on the face of the slats Db (see Fig. 8b). The bar I9 is provided with a connectingterminal I9b, leading to the transmitting circuit. The metallic plate 18a is also provided with a terminal connection I8b leading to the transmitting circuit. A perforated band A is trained over rolls 3a and 9b and passes securing greater efliciency;

transmitting circuit in between the spring'contact fingers I! and'the cathode pins Ea of the photo-electric cell groups.

The band A may be driven in any suitable manner, for example, in the manner shown in Figure 2; and an intermittent drive connection is provided between roll- 9a and roll Ila to eifect stepby-step movement of slat-belt D. This intermittent-drive may be a combination of a single tooth gear onthe shaft of roll 9a cooperating withv a.

' multi-tooth gear on the shaft of roll Ila. The

arrangement of perforations on band A is illustrated in the lower' part of Figure 8.

Operation of the arrangementshown in Figure 6 is as follows: From an inspection of Figure 8 in connection with Figure 6, it will be seen that acircuitbetween terminal conductors I8b and I9b will be completed through one of the cells E only when a perforation in band A coincides in position with a cathode pin on a cell. Referring toFigure -8,' as the band A moves upward, the cells will be connected into the transmitter circuit in the order in which theyare numbered.

When band A travels one screen height, the intermittent drive between rolls 9a and Ila causes slat-belt D to move downward a distance slightly greater than the diameter of a perforation in v band A. Upon a movement of band Athrough another 'screen height, the entire group of cells will be again connected to the circuit in successionin the order in which they are numbered. Continued operation in this manner eflects a. step-by-step movement of the cell group downwardly across the entire picture area, and at each pbsition of the group, all the cells are scanned in succession.

From an inspection of Figure. 8, it will be ob served that due to the particular arrangement of the cells on the slatbelt, I am enabled to employ photo-electric cells having a greater diameter than the elementary area of the picture, the per-Z size of which is indicated by the size of the forations inband A. It will thus be seen that this arrangement has considerable advantage from a commercial standpoint in the manufacture of apparatus in which it is ver difiicult to produce extremely small cells.

The arrangement shown in Figure 7 is the same as that shown in Figure 6 except that the band A is placed in front of the slat-belt D and serves as a light distributor or commutator instead of an electric circuit commutator as in Figure 6.

In the arrangement shown in Figure 7 all the photo-electric cells of any given group which lie within the picture area are connected to the parallel, but only those cells which are energized byolight passing through a perforation in band A are eifective in producing photo-electric, currents for operating the transmitting apparatus. In Figure 6 all the cells within the picture area are subjected to light from the picture image, and are successively rendered operative by completion of the electric circuit through the operation of band A acting as a commutator, whereas in Figure 7 the electric circuits for the cells within the picture area remain completed, and the cells are rendered operative in succession by the action of the band A in admitting the light to the cells in proper sequence.

Both the arrangements shown in Figures 6 and 7 may be employed at a receiving station for reproducing a transmitted picture by replacing the cells E with lamps L as shown at the left in Figure 8b. As will beapparent one terminal of the filament of each lampis connected to the 'rangements of perforations in band screw-shell of the plug connector which maintains contact with the metal strip Dc on the face of the slat carrying the lamp, and the other terminal of the filament is connected to a connecting pin La extending to the rear of the slat with the strength of the signal received at any given instance. I

The flexible backing Da of slat-belt D is provided with sprocket perforations along its edges as shown in Figure 8.

In Figure 9 I have shown diagrammatically an arrangement for indicating the condition of synchronism between the transmitting and receiving apparatus. I prefer to drive the transmitting and receiving apparatus by electric motors provided with a device for the manual control of speed. In Figure 9 the numeral 20 indicates a roll for driving band B, or any other device which;

is driven at a speed proportional to the driving motor. Secured to roll 20 is a rotating arm 20a adapted to engage one arm of a bell crank lever 2| which is mounted upon a support 21a, and biased to one position by a spring 211). The other arm of the bell crank lever 2| is connected to a slidable insulating strip 22 by a link element 21c. The reciprocating member 22'is provided with a conducting strip 22a to which is connected one terminal of battery 25. A pendulum 23 mounted upon a fulcrum 23a on a support 23b is provided with an arcuate conducting member 230 to which is attached the other terminal of battery .25 in series with a lamp 2'4. I

Operation of the arrangement shown in Figure 9 is as follows: Both the transmitting and receiving stations are provided with apparatus shown in Figure 9, and the two pendulums are identical and have the same time period. The relation between the speed of rotation of arm 20a and the period of the pendulum 23 must be such that as the arm 20a causes the reciprocatin member 22 to advance towards the arcuate member 230 an impulsewill beimparted to the pendulum to keep itv swinging. It will be understood that the frequency of oscillation of the pendulum may be much lower than the frequency of rotation of arm 20a, but the frequency of the arm 20a must be equal to or a multiple of the frequency of the pendulum. So long as the driving motor is operating at the proper speed, the arcuate member 23c swings away from the reciprocating member 22 before the circuit is completed through the lamp 24, however, should the motor increase in speed, the reciprocating member 22 would be advanced towards the member 23c and a circuit would be completed momentarily causing lamp 24 .to flash. Theflashing of lamp 24 indicates j that the motor is not operating at the proper speed, and a manual adjustment of the driving motor rheostat may be made until synchronism is restored and indicated by a dark condition of the lamp.

In Figure 10a I have illustrated five different arrangements of perforations in band A in combination with band B as employed in the twoband arrangements of Figures 2, 4 and 5. Fig ure 10b illustrates a two-row arrangement of perforations in band B, with five diiferent arrangements of perforations in band A. Figure 10c shows band B in front of band A, with two ai'-.

. mounted on the shaft rangement of the perforations may be made without departing from my invention. 10

nning device is shown in Another form of see Figures 11, 12 and 13. In this arrangement, a members 26a, 28b,

plurality of shutter or door 26c, 26d, 26c, 26 26g and 2671. are pivotally mounted in a rectangular frame 21 upon pintles 23. A 15 second set of parallel doors 261', 267', 26k, 26m, 23p, 2811 and 261' are pivotally supported in'frame 21 at right angles to the first set of doors 28a to 2811.

.upon pintles 28a. Each pintle may extend beyond the frame 21 a short distance and be provided 20 with a spring 29, one end of which is secured to the frame 21 and the other end secured to the pintle '29 in .order to bias each door to its closed position. The doors 26 have a width equalto the width of an elementary area of the picture area 25 P indicated in dotted lines in Figure 11, and each door is provided with an extension 30 at right angles to the plane of the door. The form and arrangement ofrthe doors is indicated in Figure 13. The door and the extension 30 may be formed 01 30 a single piece of metal bent around and welded to the pintles 23 in a well known manner. The extensions 30 a e provided for the purpose of serving as cam surfaces cooperating with a movable door opener for opening the doors in sequence as 35 will be explained hereinafter.

Along one side of the frame 21 is arranged a chainbelt 3| trained over sprocket wheels 32a and 32b. Sprocket wheel 32a (or 321)) is driven at a constant speed from a suitable source of 40 power (not shown) A second chain-belt 33 is arranged along an adj acent side of frame 21 at right angles to chain-belt 3| and is trained over sprocket wheels 34a and 34b. Chain-belt 33 is driven by step-by-step movement by a single-tooth gear 320 is of sprocket wheel 32b cooperating with a multi-tooth gear 340 mounted on the shaft of sprocket wheel 34a.

Chain 3| is provided with a plurality of door operator fingers 31a, 31b, 3 l 0, 31d spaced along the 60 length of the chain a distance equal to the height of the picture area P. Likewise, chain 33 is provided with a plurality of door operators 33a, 33b and 33c spaced along the length of the chain a distance equal to the width of the picture area P. 55 The frame 21 is provided .with slots 21a and 21b to permit the passage of the door operators mounted on chain 3|, and slots 21c and 2141 to permit the passage of the door operators mounted on chain 33. 6

Operation of the arrangement shown in Figures 11 to 13 is as follows: As an operator on chain 3| passes through the frame 21 it engages the extensions 30 and opens the doors 26f to 261' in sequence. In a like manner, the operators on chain 65 33 engage the extensions 30 on doors 26a to 261:. in succession, however, chain 33 is operated in step-by-step movement by chain 3 I, and the drive connection is such that an operator on chain 33 maintains one of the vertical doors open while an operator on chain 31 travels the-complete height of the frame 21 and opens each-of the horizontal doors. After the uppermost horizontal door has been opened and closed, the single-tooth gear 320 engages the mum-tooth gear 34c and steps the door, and door 231 is permitted to close under the action of spring 29. In case spring 29 does not have sufficient force to close the. door, the preceding door is automatically closed by the door being ,opened by engagement with the extension 33 on the preceding door and forcing itclosed. After operator 3|a passes door 261' the chain 33 is stepped forward to open-the vertical door 26;; and permit the closing of door 28]. The door -26g-now remains open until the operator 3lb opens and closes the horizontal doors 26i to 261' in sequence. The foregoing operation continues until all of the elementary picture areas constituting 'side is by-passed around the the picture area P have been exposed in succession to the photo-electric cell. The cell employed in Figure ll may be thesijngle cell arrangement of Figure l, or the multiple cell arrangement in Figure 5. It. is apparent that the device shown in Figures 11 to 13 may be used at a receiving station as well as at a transmitting station.

In-Figures 14 and 14a, 1' have shown an arrangement for transmitting or receiving pictures in color. The scanning device employed in this arrangement is the same as that described in connection with Figures 2 and 211, (except for the perforations on hand A) and like parts are indicated by the same reference characters. An endless, translucent belt '36 is trained over a pair ofrolls 31a and 31b, and oneside of the film is arranged. to pass in front of the objective lens :3 as indicated at 36c, while the other objective lens by rolls 38a and 38b. The film 36 is made up of horizontal-sections 36c, 36d and 38e,"being colored blue, yellow, and red, respectively. These sections are repeated around the entire'film in the order stated above. Each colored section is of a width equal to the width of an elementary area of-the picture area. The'scanning band A has groups "of three perforations in the same order as the colors appear on the sections of film 36, i. e., blue, yellow and red, and is caused to move past the plane of the image area in the same directionand at the same rate as the film 36. The arrangement of the perforations on band A, is shown in Figure Me. The driving motor is attached to. the shaft of roll 9, and roll 31a is driven from roll 9 by suitable-gearing including a shaft 39. The perforations in band B may be arranged in accordance with any of the arrangements shown in Figures 10a and 1012. Band B is driven from the driving roll of band A in step-by-step movement as described above in connection with Figure 2. The front of the camera is provided with 'ilight-proof slit to exclude the light from the wrong film sections.

Operation of the arrangement shown in Figures l4 and 14a. is as follows: For each position of the band 3, band A travels a distance equal to three times the screen height, and each perforation in band B is traversed by three perforations in band A corresponding tothe three primary colors. 7 The result of band B'operating in connection with band A and the three colored films 36, is that every exposure of a perfo a ion of band B has impressed upon it three perforations of band A. Thus, when -a red section of the film is in front of the lens, the first of the series of three perforations of band A allows a red light beam to pass through the band B to the cell,'in thecase of a transmitter, and in the case of a receiver, allows a red light to pass to the projection screen. In a like manner a yellow'and a blue light beam are permitted to pass by the second and third of the series of the three perforations of band A, and these three colors 10 blending together produces the desired natural color. For example, if an orange colored object be placed before the lens of the transmitter, the red section allows its component of the object color to be transmitted, while the yellow section allows its component to be transmitted, each setting up a current in the photo-electric cell, while the blue section produces no effect. In a smilar manner, the natural colors are reproduced in the receiver set.

Instead of employing a-separate transparent band 36 to produce the three primary colors, I may make band A- of transparent material with the places normally occupied by the perforations colored the proper colors and having the band will be an opaque band having transparent spots arranged in accordance with the perforaphotographs, drawings, .sketches and the like, as

commonly known as still? pictures at any desired rate, and that by speeding up the rate of scanning operation to a rate of from 12 to 15 pictures per second, the arrangements may be employed for the transmission of moving pictures, which-operation is commonly referred to as television.", In the appended claims, the

word picture" is used in a generic sense to include either a still pictln'e or a moving picture.

While I have selected specific embodiments of .my invention for the purpose of illustrating the same, it will be understood that variouschanges and modifications may be made in these embodi- 'ments without departing from the essence of the invention.

What Iclaim is 1. In a, picture transmission, system, the combination of means for forming image of a picture to' be transmitted, a light-sensitive cell arranged to be influenced by light from said im-' age,'two light-screens. interposed between said image and cell, each having a plurality of apertures formed therein of a size equalto an elementary areaof said image, means for advancing one of said screens across said image area in step-by-step movement, and means for moving saidsecond screen to cause-apertures in said second screen to concide with the apertures in said first screen in succession for each step of connections, means'for forming an image of a picture to be transmitted upon said light-sensitive surface, and means for successively connecting saidlight-sensitive elements in circuit with-the. transmitting apparatus comprising a remainder of the band made opaque, that is, the

pair of superimposed bands interposed between contacts in said electric circuits and each havng a plurality of apertures formed therein and being adapted to maintain said contacts open except upon coincidence of apertures in said pair of bands. r

3. In a picture transmission system, means for forming an image of a picture to be transmitted, a light-sensitive cell, means for exposing said light-sensitive cell to light admitted from each elementary area of said image in successiomand means for successively interposing color filters or three diiferent colors in the rays forming said image during each'exposure or an elementary area. 4. In a picture transmission system, a scanning device comprising two superimposed elements each provided with a plurality oi apertures, means for moving one step movement,-and means for moving the second element to cause the apertures therein to coincide with the apertures in the first element in succession for each step of movement of the first element.

5. In a picture transmission system, the combination of a photo-electric cell having a flat light-sensitive surface large enough to receive a complete image oi a picture 'to be transmitted, means for forming an image of said picture upon the surface of said cell, light interceptingmeans arranged immediately in frontal said cell, said means comprising two light screens each having a plurality of apertures iormed therein of a size equal to an elementary area of said image, means for producing relative movement between said screens for causing said apertures to coincide successively over different elementary areas of said cell. I

6. A scanning apparatus consisting of two media traversing an image area, each oi said media being provided with light-permeable areas, the said light-permeable areas or the first medium being arranged parallel to each other and at an angle to those on the second of said-media, the first or said media moving at a slower rate speed and having its light permeable areas spaced approximately an image-width apart and torming a light beam or rectangular cross-section, the

second of said media moving at a greater rate otand having its light permeable areas spaced a traction oi an image-width apart, and causing by their repeated, rapid intersection with said rectangular light beam a travelling light point which traverses the said image area in the form 0! a series of transverse lines of varying intensity in accordance with an image.

'1'. A scanning apparatus consisting of two media traversing an image area in opposite directions, each or said media being provided with light-permeable areas, the said light-permeable areas on the first of said media being placed parallei to each other and at an angle to those on the second of said media, the first of said media moving at a comparatively slow rate as speed and having its said light permeable areas spaced an image-width apart, said light permeable areas in turn forming a light beam of rectangular cross sectional area, the second or said media moving at a comparatively high rate of speed and having its light permeable areas spaced a fraction of a picture width apart in order to increase the number of scanning lines in the image area, and causing by their repeated, rapid intersections with the said rectangular light beam a travelling light point, which traverses the form of a series of transverse lines of varying of said elements in stepbyand point where the'ssid image area in v intensity in accordance with an image.

8. A scanning apparatus consisting 0! a plurality of moving media coacting with an optical element to produce an image, each of said media being provided with a series of light-permeable areas consisting of a plurality of parallel lines, the lines on one of saidmedia being disposed at an angle to those on the second of said media, each of said lines media coinciding with one of said openings in the second of said media to produce a distinct, individual' light beam or an intensity corresponding to the intensity of the image at the portion of the image in which it is produced, which is gradually produced by'the gradual coincidence of said openings and which is gradually extinguished by the gradual noncoincidence of said openings, while an adjacent opening on each of said media successively coincide to produce an adjacent, individual light beam of an intensity corresponding to the intensity of t e portion of the image in which it is produced, until a succession of such gradually produced, individual light beams has been produced and extinguished successively throughout said image area, thus constituting a visual image.

9. A scanning apparatus consisting of a plurality of oppositely moving media coacting with 80 an optical element to produce an image, each of said media being provided wit a series of lightpermeable areas consisting of a plurality of parallel lines, the lines on one of said media being disposed at an angle to those on the second of 85 said media; each of said lines being composed of a plurality of openings, one of said openings in one of said media coinciding with one of said openings in the second of said media to produce a distinct, individual light beam of an intensity 40 corresponding to the intensityoi the image at the it is produced, which is gradually produced by the gradual coincidence of said openlugs and which is gradually extinguished by the gradual noncoincidence of said openings,

to the intensity of the portion of the image in which it is produced, until a succession of such gradually produced, individual light beams has been produced and extinguished successively throughout said image area, thus constituting a yisual image. v 10. A scanning apparatus consisting of two media traversing an image area, each of said media being provided with light-permeable areas consisting 01' rows of openings, the said lightpermeable areas of the first medium being arranged. parallel to each other and at anangle to those on the second 01' said media, the first or said media moving at a slower rate of speed and having its light permeable area spaced approximatelyan image-width apart and forming a light beam of rectangular cross-section but consisting of a series of light beams formed by said openings, the second or said media moving at a greater speed and having its light-permeable areas spaced a fraction of an image-width apart, and causing by their repeated intersections with said rec- 7 tangularly grouped light beams a series or distinct, individual light beams of varying intensity throughout an image area.

r'. L. MIDDELRAAD. .75

being composed of a plurality 10 of openings, one of said openings in one or said 

